The present invention relates to a multicoordinate sensing head of the type comprising a sensing pin, a support member, and means for detecting deflection of the sensing pin.
A variety of multicoordinate sensing heads for the sensing of workpieces in several directions are known in the art. In general, such sensing heads can be subdivided into two categories. In the first category, the sensing pin is deflected angularly when it is deflected perpendicularly with respect to its axis. In the secondary category, the sensing pin is movably mounted by means of straight guides such that the axis of the sensing pin remains parallel to its original orientation under perpendicular deflection of the pin. In German patent DE-PS No. 22 42 355 there is described an electronic multicoordinate sensor which is characterized by a combination of individual features. A torsionally rigid array of play-free and friction-free linear guide systems forms a flat or spatial coordinate system. This arraying of linear guide systems one on another improves the state of the art as represented in the background portion of the specification of this patent. The system disclosed in this patent, however, still is characterized by certain disadvantages, since an arraying of spring parallelograms one on another results in one linear guide system which builds on the accuracy of the previously mounted straight guide system. In cases in which two or more linear guides are arrayed one on another (as for example on a cross table) the individual linear guide systems must be manufactured with extreme precision in order to meet necessary accuracy requirements. Such extreme precision in general results in unusually high construction and manufacturing costs. Furthermore, it is a peculiarity of linear guide systems which incorporate spring parallelograms, that, on deflection, the separation between plates which move parallel to one another changes. This effect is negligibly small only in the case of very small deflections.